Properly configuring firewalls greatly increases your system security

Redhatlinux provides firewall protection for increased system security. Firewalls exist between your computer and your network to determine which remote users on your network have access to the resources on your computer. A properly configured firewall can greatly increase your system security.

Choose the appropriate level of security for your system.

High

If you choose advanced, your system will not accept connections that are not specifically specified by you (except for the default settings). Only the following connections are allowed by default:

DNS response

DHCP any network interface that uses DHCP can be configured accordingly. If you choose Advanced, your firewall will not allow the following connections:

1. Active state FTP (the passive state FTP used by default in most client machines should work correctly.) )

2.IRCDCC file transfer.

3.RealAudio.

4. Remote X Window System client.

If you want to connect the system to the Internet, but do not intend to run the server, this is the safest choice. If additional services are required, you can choose "Custom" to specify the services that are allowed through the firewall.

Note: If you choose to set up intermediate or advanced firewalls in your installation, the network authentication Method (NIS and LDAP) will not work.

Intermediate

If you choose Intermediate, your firewall will not allow your system to access certain resources. Access to the following resources is not allowed by default:

1. Ports below 1023-These are the standard ports to keep, and are used primarily by some http://www.aliyun.com/zixun/aggregation/18477.html "> system services, such as FTP, SSH, Telnet, HTTP, and NIS.

2.NFS Server Port (2049)-NFS is disabled on both the remote server and the local client.

3. The local X Window system that is set up for the remote x client is displayed.

4.X Font Server port (XFS is not listening on the network; it is disabled by default in the font server).

If you want to allow access to resources such as RealAudio, but still want to block access to common system services, select "Intermediate". You can choose "Custom" to allow specific services to pass through the firewall. Note: If you choose to set up intermediate or advanced firewalls in your installation, the network authentication Method (NIS and LDAP) will not work.

No firewall

No firewall gives full access to no security checks, and security checks are disabled for certain services. It is recommended that you select this only if you are running in a trusted network (not the Internet), or if you want to do a detailed firewall configuration later.

Select Customize to add trusted devices or allow other access interfaces.